Remove activation by `SetNextItemShortcut()` causes tooltips to flicker

[achabense]

Version/Branch of Dear ImGui:

Version 1.92.6 WIP

Back-ends:

imgui_impl_dx9.cpp + imgui_impl_win32.cpp

Compiler, OS:

Windows 10 + MSVC

Full config/build information:

No response

Details:

ImGui::SetNextItemShortcut() will cause tooltip to flicker, no matter whether it's for the item itself or tooltip for other items.

I'm not familiar with shortcut APIs (found this as soon as I tried the function), so maybe I'm missing something?

Screenshots/Video:

No response

Minimal, Complete and Verifiable Example code:

static void test() {
    if (ImGui::Begin("Window")) {
        // Sleep(50);
        // I guess it's related to `ImGuiInputFlags_Tooltip`?
        ImGui::SetNextItemShortcut(ImGuiKey_R/*, ImGuiInputFlags_Tooltip*/);
        ImGui::Button("Button 1");
        // When activated: will be "shifted" for some (one?) frames (but won't disappear).
        if (ImGui::BeginItemTooltip()) {
            ImGui::Text("Press R to activate this button.");
            ImGui::EndTooltip();
        }
        ImGui::Button("Button 2");
        // When activated: will disappear for some (one?) frames.
        if (ImGui::BeginItemTooltip()) {
            ImGui::Text("Press R to activate button 1.");
            ImGui::EndTooltip();
        }
    }
    ImGui::End();
}

[achabense]

static void test() {
    if (ImGui::Begin("Window")) {
        // Sleep(50);
        ImGui::SetNextItemShortcut(ImGuiKey_R);
        ImGui::Button("Button 1");
        ImGui::SameLine();
        ImGui::Text("%d%d", (int)ImGui::IsItemHovered(), (int)ImGui::IsItemHovered(ImGuiHoveredFlags_ForTooltip));
        ImGui::Button("Button 2");
        ImGui::SameLine();
        ImGui::Text("%d%d", (int)ImGui::IsItemHovered(), (int)ImGui::IsItemHovered(ImGuiHoveredFlags_ForTooltip));
    }
    ImGui::End();
}

The function directly affects IsItemHovered().

So SetNextItemShortcut actually activates first button and cause the second button to lose the hover. So maybe it's intentional to see the second case (tooltip for button 2)? (Sigh, I wanted to use this instead of Shortcut only for it's rendering effect (lighting up)). But the first case (tooltip for button 1) still seems problematic.

[achabense]

For the first case (Button 1; same item), I think it's indeed a bug and should be fixed.

For the second case (Button 2; different item), I think the library should document the effect on hover test for other items (especially tooltips).

(My original goal (to highlight without actually activating the item) can be achieved by replacing SetNextItemShortcut with Shortcut + NavHighlightActivated.)

[ocornut]

[1] The first issue is because the remote activation affects the result of NavCalcPreferredRefPosSource(), and that result is used to position tooltips (they are positioned differently when using mouse vs using keyboard, which is desirable).

static ImGuiInputSource ImGui::NavCalcPreferredRefPosSource()
{
    ImGuiContext& g = *GImGui;
    ImGuiWindow* window = g.NavWindow;
    const bool activated_shortcut = g.ActiveId != 0 && g.ActiveIdFromShortcut && g.ActiveId == g.LastItemData.ID;

    // Testing for !activated_shortcut here could in theory be removed if we decided that activating a remote shortcut altered one of the g.NavDisableXXX flag.
    if ((!g.NavCursorVisible || !g.NavHighlightItemUnderNav || !window) && !activated_shortcut)
        return ImGuiInputSource_Mouse;
    else
        return ImGuiInputSource_Keyboard; // or Nav in general
}

And in NavCalcPreferredRefPos():

    ImRect ref_rect;
    if (activated_shortcut)
        ref_rect = g.LastItemData.NavRect;
    else if (window != NULL)
        ref_rect = WindowRectRelToAbs(window, window->NavRectRel[g.NavLayer]);

Code added in 197f890. Note the comment (+ code was reworked spread over two functions since initial commit).

I don't quite remember off-hand the reasoning for those paths....
If I change both functions to use const bool activated_shortcut = false;// g.ActiveId != 0 && g.ActiveIdFromShortcut && g.ActiveId == g.LastItemData.ID; I don't see the issue right now but there must be one.... need to understand why I added this in the first place.

For reference, the g.NavDisableXXXX flags referred to in the comment were changed to !NavCursorVisible and NavHighlightItemUnderNav.

[2]
Here the IsItemHovered() flag is affected because g.ActiveId is true for one frame.
Remote activation works when another item is active, but it steals active id so that's not great.
Ideally we would want at least items based on ButtonBehavior() to handle remote activation without stealing active id anyhow.

[3]

My original goal (to highlight without actually activating the item) can be achieved by replacing SetNextItemShortcut with Shortcut + NavHighlightActivated.)

Yes indeed if you only want to remove highlight for "documentation" purpose you shouldn't activate. I also don't know why you would use SetNextItemShortcut() ? Or you mean using SetNextItemShortcut() on button 1 (the only with the shortcut) and using NavHighlightActivated in button 2 tooltip (the only that highlight) ?
If you have more question about specifically highlighting please open a separate issue so we can tackle that separately from the remote activation side-effects of [1] and [2].

Modified repro

    ImGui::Begin("Issue #9138");

    // ::Sleep(50);
    // I guess it's related to `ImGuiInputFlags_Tooltip`?
    ImGui::SetNextItemShortcut(ImGuiKey_R/*, ImGuiInputFlags_Tooltip*/);
    ImGui::Button("Button 1");
    // When activated: will be "shifted" for some (one?) frames (but won't disappear).
    if (ImGui::BeginItemTooltip())
    {
        ImGui::Text("Press R to activate this button.");
        ImGui::EndTooltip();
    }
    ImGui::Button("Button 2");
    // When activated: will disappear for some (one?) frames.
    if (ImGui::BeginItemTooltip())
    {
        ImGui::Text("Press R to activate button 1.");
        ImGui::EndTooltip();
    }

    ImGui::SetNextItemShortcut(ImGuiKey_F1, ImGuiInputFlags_RouteOverActive);
    ImGui::Button("Button F1");
    static char buf[128];
    ImGui::InputText("InputText", buf, 128);

    ImGui::Separator();

    ImGui::SetNextItemShortcut(ImGuiKey_T);
    ImGui::Button("Button 1b");
    ImGui::SameLine();
    ImGui::Text("%d%d", (int)ImGui::IsItemHovered(), (int)ImGui::IsItemHovered(ImGuiHoveredFlags_ForTooltip));
    ImGui::Button("Button 2b");
    ImGui::SameLine();
    ImGui::Text("%d%d", (int)ImGui::IsItemHovered(), (int)ImGui::IsItemHovered(ImGuiHoveredFlags_ForTooltip));

    ImGui::End();

[ocornut]

About [2] remote activation stealing active id.
This is part of a201af7. Note that this added in ItemHoverable()

    if (g.ActiveId != 0 && g.ActiveId != id && !g.ActiveIdAllowOverlap)
++      if (!g.ActiveIdFromShortcut)
            return false;

Logically the same at least should be added in IsItemHovered(), so I made that change with: 3389dfd.

This fixes the visible effect of [1.2] and of [2] and is consistent with the code in ItemHoverable().

Remaining:

• The [1.1] bug discussed above as NavCalcPreferredRefPosSource() changes to keyboard for 1 frame.
• The "ideal" change would to be manage to make single-frame remote activation not lose active id, but this is going to be more tricky to implement.

[achabense]

I also don't know why you would use SetNextItemShortcut() ? Or you mean using SetNextItemShortcut() on button 1 (the only with the shortcut) and using NavHighlightActivated in button 2 tooltip (the only that highlight) ?

About [3], the full background of this issue is:

1. I have some buttons with shortcuts. To get things work, using Shortcut (or lower-level functions) is enough. However, I want to also highlight the buttons to make the effect of shortcuts more obvious (to let users see they have activated a shortcut).
2. So just for highlighting purpose, I tried SetNextItemShortcut and it seemed to work (the highlighting effect).
3. However, in my program I also use tooltip windows frequently (using tooltip to show zoomed view of images), and some shortcuts are designed to be allowed when the tooltip is on. Then I noticed the tooltip getting disabled when I press the shortcut.

(In short, my original goal was to highlight the shortcut button without affecting tooltip for other items (similar to case 2). Case 1 was discovered when I make repro code.)

[ocornut]

So your main issue should be solved for most cases now, apart from the [1.1] case (same item, tooltip moves for 1 frame) which am I working on.

I am struggling to find many cases where the !activated_shortcut test makes sense and might simply disable it for now.

This case however requires the logic:

    ImGui::SetNextItemShortcut(ImGuiKey_F3, ImGuiInputFlags_RouteGlobal);
    if (ImGui::Button("OpenPopup (F3)"))
        ImGui::OpenPopup("Popup");
    if (ImGui::BeginPopup("Popup"))
    {
        ImGui::Text("Hello");
        ImGui::EndPopup();
    }

Without the if (!activated_shortcut) logic, pressing F3 opens the popup near the nav or mouse cursor, not near the button.
Since its a shortcut on an item it seems logical that it would be next to the button. I could however imagine adding flags to OpenPopup() to specify where to locate the popup by default.

I'll try to find a way to fix those.

[ocornut]

I pushed a fix 7a02f4b.